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U2 3D

For the past 30 years, only audiences at U2 concerts have known what it was like to experience one of the band's live shows. But with the recent release of their newest concert film, U2 3D, that's all changed. The first live-action multicamera 3-D feature shot in HD, U2 3D places movie audiences smack in the middle of the crowd and onstage with the band, giving fans an experience almost as rich as attending in person surrounded by 90,000 other fans. Released by National Geographic Entertainment and directed by Catherine Owens and Mark Pellington, the movie can only be seen in 3-D, either in digital cinema-equipped theaters using REAL D 3-D projection or in IMAX 3-D.

The film was shot over a three-week period in March 2006, during the group's Vertigo tour in South America. Seven live concerts were filmed: two in Mexico City; two in Sao Paolo, Brazil; one in Santiago, Chile; and two in Buenos Aires, Argentina. An additional “phantom shoot” — sans audience — was filmed early the first night in Buenos Aires, with cameras placed close up onstage to permit such “macro” shots to be captured without camera operators interfering with the view of audience members.

For audio recording, executive audio producer (and one of the film's producers) John Modell of 3ality Entertainment enlisted the help of two U2 alums: co-producer and recordist Robbie Adams and music producer and mixer/re-recording mixer Carl Glanville. Adams has worked with the band on and off since 1989, engineering and mixing their Achtung Baby and Zooropa albums, as well as mixing front of house with U2 veteran Joe O'Herlihy and recording on numerous tours and live DVDs. Glanville, with the band since 2002, had produced and mixed two live concert DVDs for U2, as well as numerous other remixes; this was his first re-recording project. “That was the hallmark of the whole production — to work with guys who've been working with the band forever — rather than sending in some outside company with a truck,” notes Modell.

As a base, Adams used the band's live miking setup, comprising mainly Sennheiser 421s; Shure SM58 Betas, SM57s and RF58As (for Bono's vocals); AKG 414s; and Countryman DI boxes. Venue/audience ambience was picked up by Audio-Technica AT4073As and AKG 414s. Additional spot mics, mostly SM57s, were placed at various locations along the stage's tendril-like ramps — down which bandmembers would wander during certain songs — for pickup of individual audience clusters. “It really brings quite a lot and helps suck you into the movie,” Adams explains, “so that when you see a person screaming on-screen, that's the person you're hearing.”

Placement of audience/ambience mics was crucial to the 3-D experience. “The Latin American audiences are very vocal and exuberant,” notes Modell. “We knew that was going to be a big part of the movie.” The varying architecture of the different venues posed a challenge — both to Adams for recording and, later, for Glanville in mixing when trying to match ambiences from different recordings. “In one venue, we might point a mic at a wall near a large audience section, though that place doesn't exist in another stadium,” Adams says. “And one stadium might have a roof, while another is smaller, is shaped like a dish and has no roof. So you're totally guessing — you do the best you can and then deal with it later.”

The microphone signals were split through a Clair Bros. splitter to both stage and local racks containing the digital mic preamps for the DiGiCo D5 FOH desk, as well as the other D5 used for the monitor system. An additional set of audio splits fed the Digidesign VENUE console (operated by longtime U2 monitor engineer Dave Skaff), from which the signal was drawn for recording.

Adams recorded the earlier shows on his Steinberg Nuendo system, inputting 96 channels until it was discovered that additional inputs would be required for the additional ambience mics, totaling 110 inputs. So they switched to Pro Tools HD. In fact, for multiple redundancy, two Pro Tools rigs were used, the second acting as a backup along with the Nuendo.

Interestingly, Modell found that there was no direct way to sync picture and sound recording together with a digital clock. “Front of house would have had to sync their whole show to our camera clock, and that was not going to happen,” he says. To solve the problem, a stereo FOH mix was recorded to both systems. Editor Olivier Wicki then imported that mix into his Avid editing system, which was then output as an OMF (Open Media File), which Adams and Glanville then imported into their Pro Tools session, visually aligning transients of the FOH mix with their own recording of that mix in the Pro Tools session.

In addition, the click-track used by the musicians was also recorded to both systems; Adams and Glanville used it to make slight adjustments, as needed, to Wicki's OMF. “He would put together what he thought was the closest version of the thing,” Glanville explains. “But Olivier's not a music editor, so every once in a while he might skip a beat or come in halfway through a beat because he couldn't hear it clearly in that mix.” The team would make whatever slight adjustments were required and send the OMF back to Wicki, who would then regenerate picture and return the corrected file back to the audio team.

PUTTING IT ALL TOGETHER

As mentioned, the film comprises recordings made at a total of eight performances from four different venues that were seamlessly edited together, both in picture and sound, to appear to be from a single source. No overdubs were done by the band, which, Modell notes, “is a real testament to the band's talent and accomplishment.”

Adams and Glanville edited and mixed the soundtrack over a period of more than a year — from July 2006 to October 2007 — at Effanel Music in New York City, taking full advantage of the studio's Digidesign ICON console. “It's the only ‘real’ 5.1 room that's of a size [that] music engineers who are used to making records would appreciate,” says Glanville. “We knew the scope of this project was going to require some serious hardware and a room that was specifically built for 5.1.”

Glanville notes that for concert films, the picture is usually conformed to whatever performance of a song is deemed best, but in this case that wasn't possible due to picture limitations at certain venues. Production was limited to only one or two 3-D camera systems on all but the Buenos Aires shows (to avoid multiple cameras block-ing audiences' views), which left director Owens and editor Wicki with only a single camera angle with which to work for songs from those nights' performances.

“We realized that because the picture department wanted to put together the best collection of shots they possibly could for any one song, we couldn't just pick the best version of the song and have them conform picture to it,” says Glanville. “It was clear we were going to have to conform our audio to their picture.”

Complicating matters, says Modell, is that the band — Bono, guitarist The Edge, bassist Adam Clayton and drummer Larry Mullen Jr. — varied the phrasing in their performances from show to show, and that the 3-D film featured 10 to 20-second shots (as opposed to the customary quick cuts in concert films). “So you don't have a choice but to use the real audio from whatever picture you're seeing, because you'll run into lip-sync and instrument-sync issues that will be obvious to the audience,” Glanville explains.

The team then developed an “assembly line” of sorts at Effanel, with Adams constructing Pro Tools playlists of the recordings in one room and Glanville mixing in the other. It was decided to first assemble a playlist that matched the picture, shot for shot, of each song: a master wide shot, say, from Mexico City, with its associated audio recording, and then a close-up of The Edge playing a guitar riff from Buenos Aires with its recording, etc.

Adams' playlist contained the full group-ing of all tracks from each night's performance of each song, stacked one below the other on the list, allowing him to comp the track group of a night's show to match the image appearing onscreen.

“We just built an exact replica of what they had, and then started looking at what that meant to the performance, sonically,” Glanville explains. “Then, once we'd done that, we said, ‘Okay, now let's do another version of that edit, and pull out any unnecessary edits.’” Glanville found that, while it was literally accurate to switch to the recording from a different show, say, for a quick cut to a group of audience members singing along, doing so would unnecessarily interrupt a guitar or vocal performance.

“We spent a lot of time going through each song and removing those kinds of cuts,” says Adams. “For the most part, the main body of a song was from the single night's recording.” Sometimes, though, the picture might cut to, for example, The Edge playing his guitar lead or a drum bit from a different show. In many such cases, because the band was playing to a click track — providing a uniform rhythm for each song from show to show — Adams was able to simply reselect from within his comp the guitar track for the song appearing onscreen while bringing in the remainder of the backing track from the master performance.

Switching between performances wasn't always so simple, however, where ambience was concerned — particularly where Bono's lead vocals were involved. If a master shot of one night's performance, with its associated venue ambience, cut to a close-up of Bono singing a line taken from a different night's show, with its own associated ambience, Glanville was forced to use the recording from the close-up's shot during that close-up and then carefully switch back to the master when the close-up was over.

“What I ended up having to do was group his vocals, with all the audience mics, and then build a vocal performance, so that every time you saw him I could switch to a different playlist that included all of the audience mics. So when the vocal switches, his voice is always in the ambience,” Glanville says. He then staggered the edits of the ambient mics — anywhere from a millisecond to five seconds — to crossfade smoothly between the two takes, helping to mask any differences in echo/delays caused by differences in venues.

MIXING FOR 3-D

While mixing a concert film into 5.1 surround is not new, mixing one for 3-D is, requiring a different approach from that employed for a “flat” (2-D) film. “In 2-D,” explains Adams, “generally most of the action is happening in the middle of the screen. In 3-D, you've got so much detail: There's something happening in the top of that corner or that corner. If there's something happening in one corner, people will be looking there, so you put a little voice in. People watch it completely differently — it taps into their brains in a completely different way.” Adds Modell, “We had only one rule: What feels real?”

This is not to say that a 3-D 5.1 mix means things flying all about the auditorium. “It means if you cut to a close-up shot of The Edge, you pull the guitar forward slightly in the mix,” Modell notes. “Not in a gimmicky way. The idea is that both the visual part and the audio part should become transparent as media. If you're feeling a bunch of gimmicky stuff going on, it will pull you out of the experience.”

For Glanville, it was all a matter of finding the right moments, many of which were fairly organic. “When you see a presentation on a 50-foot-wide screen, and you suddenly hear Bono's voice come out of the left speaker, your eye is immediately drawn to the left side of the screen. You turn your head and out pops Bono from the edge of the screen, walking up the ramp, and then the audio tracks him to the middle of the stage. It's little moments like that that make it a very different experience from something that you would see in 2-D.”

Glanville also played with dynamics and ambience, and took advantage of the SM57 spot audience mics to create a different experience for the viewer. At the end of “Miss Sarajevo,” says Glanville, “Robbie had the idea of pulling out all the ambience, where you see Bono slowly walking up the ramp.” Adams adds, “He's just sung his heart out, and as he walks back, he just strikes a lonely figure. There's all these people scream-ing out his name and he can't even hear them. It just lets you get inside his head for that moment.”

Indeed, the audience mics played a crucial part in the 3-D experience, particularly with this band's following. “There's so much happening with a U2 crowd during the body of the song that as soon as you strip that out, the soul just disappears out of the whole performance,” says Glanville. “There's too much interaction between the two to just let it go. If there was a night where a crowd really sung their hearts out, we made sure to fish that out and use it, to really give you a sense of what it's like to be in that crowd.”

To counter the effects of unpredictable multiplex theater sound systems, the team spread bass material throughout the mix. “We were worried about relying too much on the subwoofer channel to give us the bottom end of this picture,” explains Modell. “This is different from a normal picture, where it's 90 percent dialog with the odd crash or gunshot or boom. This is driving eighth notes the entire time and a constant kick drum with a lot of bottom and energy. If we relied on the subwoofer to give us a lot of that, we'd be hosed in a lot of theaters.”

The case was different from IMAX 6 masters, where theaters have a bass-management system to take full advantage of low frequencies. “We actually brought a Pro Tools system into two IMAX theaters in Los Angeles and essentially remastered it for IMAX right in the theater,” Modell says.

In October, over a three-week period, the team reconvened at Warner Bros. Dub Stage 6 to do the film's re-recording. “Dub 6 has the largest ICON console in the world,” Modell says. “And having done all this work in New York on the ICON, it was great to just come and open stuff up and not have to wrestle with remapping anything.”

Glanville's stem layout comprised drums, bass, guitar, Bono guitar, Bono vocal, Edge vocal, keyboards, audience and supplemental audience. “Sometimes we'd split the audience across two sets of tracks, just to feather in some extra sounds to make transitions work between the songs,” he explains. Gaps between songs were also extended slightly. “It was felt that to have the songs just keep hitting you one after another like that in the movie theater could end up being a bit overwhelming. Adding an extra five seconds in between some of the songs gives you that little moment to come down from what you've just heard and then get ready for the next thing.”

There were actually two sets of stems — one dry and one containing the effects — allowing Glanville to rebalance at Warner Bros. as needed. “And that amounted to about 230-odd tracks of audio,” he adds.

U2 3D was a project of “firsts” on many fronts, Modell notes. “It's the first digitally captured 3-D live action film of its kind, the first time zoom lenses were ever used in 3-D, and it was Carl and Robbie's first re-record mix. And because it had never been done before, there were no rules to break. It was a wide-open canvas. And it was Carl and Robbie's creativity and meticulousness that made it happen.”